1) Field of the Invention
The present invention is directed to the field of gas controls, and in particular to an improved slow opening gas valve having an expansible auxiliary chamber connected to an expansible control chamber by a metering orifice to slow the expansion of the expansible control chamber and thereby slow the opening of the gas valve.
2) Description of the Related Art
It is well known that gas valves of the type to which the present invention relates are configured to provide gas at an outlet for ignition at a specific pressure level. In many of these gas valves, the amount of gas provided at the outlet at the time ignition takes place causes an undesirable audible ignition. This audible ignition results from the rapid opening of the gas valve which causes excessive gas build-up in the combustion chamber of for example, a furnace, before ignition. Thus, many of these "fast" open gas valves introduce too much gas before ignition takes place, thereby causing a very rough and/or audible ignition. In addition to producing this undesirable audible ignition, these gas valves may create large flames upon ignition which could be dangerous.
A variety of gas valves are known in the art for providing slow opening valves and ignition at lower gas pressures. In general, however, many of the known-gas valves do not provide a sufficient duration of continuous valve opening and further do not provide a smooth and gradual opening of the gas valve. Additionally, these gas valves are generally complex in both design and operation, thereby increasing the likelihood of problems during operation.
Some of these known valves attempt to restrict the flow of gas to the operating or control gas side of a regulator diaphragm, while others add tortuous paths to the operating side of a regulator diaphragm. Still other valves add second diaphragms to regulate operating pressure or utilize solenoids in connection with pumps to slow the opening of the valves. Finally, other known gas valves include pressure relief valves or regulated by-pass valves for controlling gas pressure.
Generally, the known gas valves which include a second diaphragm, do not use that second diaphragm to slow the opening of the valve, but utilize the diaphragm to control operating pressure or venting of the valves. Overall, these gas valves are relatively complex, which may result in problems with reliability. Further, these gas valves fail to provide both a slow and continuous smooth opening of the valve. Thus, an undesirable audible or rough ignition may still occur.
What was needed was a gas valve with a simple design, that could be produced inexpensively, and that not only provided gas flow for lower pressure ignition, but also provided gas at a continuously and smoothly increasing rate to avoid undesirable rough or audible ignitions.